Controller for electric motors.



N0. 67!,490. Patent'od Apr. 9, I90l. W. B. POTTER.

CONTROLLER FOR ELECTRIC MOTORS.

(Appiication filed Doc. 30, 1897.)

(No Model.)

UNITED STATES PATENT OFFICE.

WILLIAM B. POTTER, OF SOIIENEOTADY, NEIV YORK, ASSIGNOR TO THE GENERALELECTRIC COMPANY, OF NEW' YORK.

CONTROLLER FOR ELECTRIC MOTORS.

SPECIFICATION forming part of Letters Patent N 0. 671,490, dated-April9, 1901.

Application filed December 30, 1897- Serial No. 664,595. (No model.)

T0 at whom, it may concern:

Be it known that I, \VILLIAM B. POTTER, a citizen of the United States,residing at Schenectady, in the county of Schenectady, State of NewYork, have in vented certain new and useful Improvements in Controllersfor Electric Motors, (Case No. 648,) of which the following is aspecification.

In the well-known series-parallel controller it is customary to use thesame resistance for controlling the motors in parallel that is employedwhen the motors are connected in series. With motors of moderatecapacity, requiring only a limited current, this arrange ment issatisfactory; but when the motors are large, such as are employed onlocomotives, and require a heavy current the current-carrying capacityof a resistance which is amply sufficient when the motors are connectedin series is too small when the motors are connected in parallel. Forexample, assume that a current of two hundred amperes at five hundredvolts will flow through four motors when connected in series with oneanother and the resistance and that the controlling resistance isdesigned to carry this amount without excessive heating, these samemotors when connected in parallel groups with two motors in series ineach group should receive a total current of four hundred amperes at thesame voltage; but if it should be attempted to reduce the resistance inthe motor-circuit by merely cutting out a portion of the same resistancewhich is used in the series connection this resistance Would not be ableto carry the four hundred amperes, since it is designed to carry onlytwo hundred amperes without excessive heating. In order therefore toadjust the rheostat constituting the resistance for the parallelconnection, it is necessary that its current-carrying capacity should beincreased at the same time thatits resistance is reduced. i

In the particular embodiment of my invention which I have illustrated itis possible to adjust the rheostat for increased currentcarryingcapacity and reduced resistance by constructing it with tworesistance-sections, one of which is used alone when the motors areconnected in series and both of which are connected in multiple when themotors are connected in parallel groups.

It is desirable to provide the same number of resistance-control]ingsteps for the motors when connected in parallel as in series and to havethe same acceleration per step in both cases.

My invention has for its object to provide in a control-circuit acontroller so arranged that its current-carrying capacity may be changedin accordance with the conditions existing in said circuit.

More specifically stated my invention comprises a motor-controller whichis so arranged that the motors to be controlled may be connected inseries or parallel with the proper amount of controlling resistance incircuit to give the same acceleration per resistance step in both cases,at the same time adjusting the current-carrying capacity of thecontrolling resistance or rheostat. This I accomplish by providing aswitch so arranged that it will reduce the controlling resistance byone-half, at the same time doubling its current-carrying capacity whenthe motors are connected in parallel. By this arrangement the motors maybe started from a standstill, either connected in series or parallel,without injury to the controlling resistance.

In the accompanying drawings I have shown my invention applied to acontroller similar to the one shown in Patent No. 583,035, dated June 8,1897, and issued to F. E. Case and myself; but for the sake ofsimplicity all unnecessary parts have been omitted.

Figure 1 is a general diagrammatic View of the controller and motorconnections. Figs. 2 and 3 are diagrams of motor combinations, and Fig.at is a detail view showing the means employed for simultaneouslyoperating the seriesparallel and resistance switches.

The controller is shown in connection with a four-motor equipment, inwhich the motors are permanently coupled in pairs and the pairs treatedas a single unit; but myinvention can be employed equally well withother forms of controllers, whether series-parallel or rheostaticmerely. The resistance-cylinder A comprises a notched metal plate A,which is mounted on an insulating-support 100 A and is adapted to bemoved into engagement with the vertical row of stationary brushes B andcut resistance B into and out of the motor-circuit. Resistance Rcomprises a set of resistance-sections, each section consisting of asmall resistance-box R, included in a separate circuit and adapted to beconnected in multiple with the other boxes for reducing the totalresistance of the circuit. WVhen all of the brushes in line 13 rest oncontact-plate A, the resistance is short-circuited and current entersfrom trolley T and passes directly to wire 1 and the motors. The motorsare arranged in pairs and provided with reversing-switches C and C. Theswitches, while being mechanically separate in the drawings, arepreferably connected for simultaneous movement. The motors are coupledin series or parallel relation by a switch G. With the parts in theposition shown the motors M to M are connected in series. Thus far theconnections and arrangement of the switches are limited to Patent No.583,935, above referred to; but in addition a separate switch D isprovided, which is adapted to reduce the resistance value of thecontrolling resist-ance by including resistance S in multiple withresistance R. Switch D is connected by wire 2 to the main circuit-wire 1and by means of the contact-brushes E operates to connect the respectivesections of the resistances R and S in multiple. It is preferable togradually decrease the amount of resistance contained in the steps asthey progress from the top to the bottom, and as resistance S can bedecreased in the same proportion the closing of switch D does nota'lfect the relative decrease between steps, but it decreases the totalresistance value of the controlling resistance or rheostat one-half, atthe same time doubling its current-carrying capacity by establishing twomultiple paths of equal carrying capacity. The arrangement of the partsis such that the closing of switch D has no effect on the motors untilswitchcylinder A is moved into engagement with the brushes, so thatresistance-cylinder A controls the opening and closing of the circuits,as before, only the total resistance is decreased by one-half.

In Fig. 4 I have shown the auxiliary resistance-switch D and theseries-parallel switch G mounted on a common support and actuated byshaft II. Contacts D and G are mounted on an insulating-support and aremoved into engagement with stationary resistance-contacts E and theseries-parallel contacts G Contact D is connected to the circuit by wire2, and contacts G are adapted to bridge the stationary contacts G Theoperation of the controller is as follows: Contact-plate A is moved intoengagement with the stationary line of brushes B. In the first positionthe circuit is as follows: Current enters from trolley T tocontact-plate A, to brush B, through the resistance R, wire 1,reversing-switch C, armature and field of motor M to thereversing-switch and armature and field of motor M to series-parallelswitch G, to reversing-switch C, to armature and field of motorM toreversing-switch and armature and field of motor M to ground. The motorsare then connected as shown in Fig. 2. A further movementofcont-act-plate A reduces the resistance of the circuit by incl uding anumber of resistance'paths in parallel with each other until the brushl3 rests upon the plate and all of the resistance will beshort-circuited. Assuming that it is desired to run the motors inparallel, switch A is brought to the position shown, switch I) movedinto contact with stationary brushes E, and switch G thrown to theparallel position. The circuit willthen be as follows: Current flowsfrom trolley T to contact-plate A, to brush B, where the currentdivides, one half passing through resistance R to wire 1 and the otherhalf through the resistance S, brush E, switch D, and wire 2 to point 3,where it unites with the current from resistance R and flows throughwire 1 to point a, where the circuit divides, one path being throughmotors M and M in series by wire 5 to switch G and to ground by wire (5.Starting again at point 4;, the second circuit is by wire 7 toseries-parallel switch G, to reversing-switch C, and thence throughmotors M and M", in series, to ground. \Vith this arrangement theresistance value of the controlling resistance o'r rheostat has beenreduced by onehalf; but the current-carrying capacity has been doubledand the motors are connected as shown in Fig. 3.

What I claim as new, and desire to secure by Letters Patent of theUnited States, is

1. In combination, a control-circuit, a rheostat therein, and means forchanging the current-carrying capacity of the said rheostat.

2. In combination, a control-circuit, a controlling-switch in saidcircuit,a rheostat therefor, and means for changing the current-carryingcapacity of said rheostat.

3. In combination, in a control-circuit, a rheostat, a controller forsuccessively connecting the resistance-sections of said rheostat intocircuit, and means for changing the current-carrying capacity of theresistancesections acted upon by the controller.

at. In combination, in a control-circuit containingelectrically-operated devices, a rheostat in circuit with all of saiddevices, and means for changing the current-carrying capacity of saidrheostat.

5. In combination, a controlling-switch, a rheostat therefor, and anadjusting-switch for changing the current-carrying capacity of saidrheostat.

6. The combination with a rheostat, of a controller for successivelyconnecting the resistance-sections of said rheostat into circuit, and anadjusting-switch for changing the value of the resistance-sections actedupon by said controller.

7 In combination, a controlling-switch, a

controlling resistance therefor, comprising a plurality of separateresistances, and a switch independent of the controllingswitch forvarying the current-carrying capacity of said resistance.

8. In combination, a controlling resistance, comprising a plurality ofsets of resistancesections, means for connecting and disconnecting therespective sections in each set, and means for cutting said resistanceinto and out of circuit.

9. In combination, a controlling resistance, comprising a plurality ofsets of resistancesections, a permanent connection leading from oneofisaid sets to a work-circuit, means for connecting the respectivesections of the remaining sets in multiple with those of the first set,and means for cutting said resistance into and out of circuit.

10. In combination, a rheostat connected to a motor-circuit, a switchfor changing the grouping of the motors, means for varying thecurrent-carrying capacity of the rheostat, and means for cutting saidrheostat into and out of circuit.

11. In combination, a rheostat connected to a motor-circuit, contactsfor cutting the rheostat into and out of circuit, contacts for changingthe grouping of the motors from series to parallel, without changing theresistance connections, and means for increasin g thecurrent-carryingjcapacity of the rheostat when the motors are connectedin parallel.

12. In an electric controller, the combinanation of a switch forestablishing a seriesparallel relation of the motors, a plurality ofswitches in the motor-circuit, one of said switches being employed tocontrol the current flowing to the motors when connected in series or inparallel, and the other switch or switches to increase thecurrent-carrying capacity of the first-named switch in controlling themotors when they are connected in parallel.

13. In an electric controller, the combination of a pair of switches forcutting resistance into and out of circuit, one of said switches beingarranged to alter the resistance step by step, the other to cut all theresistance which it controls into or out of circuit at a singlemovement.

14:. In an electric controller, the combination of a switch forconnecting the motors in series or parallel, a controlling resistance,and two separate sets of contacts for controlling said resistance, oneof said sets being controlled by the switch which connects the motors inmultiple.

15. In a controller for electric motors,which is arranged to open thecircuit between its series and parallel positions, the combination of aresistance, contacts for varying the resistance of the motor-circuit, aseparate switch for establishing a series of parallel re lation of themotors, and a resistance-switch controlled by the series-parallelswitch, for including an auxiliary controlling resistance inparallelcircuit relation with the main resistance to increase thecurrent-carrying capacity of the resistance when the motors areconnected in parallel.

16. In an electric controller, the combination of a controllingresistance composed of two elements, one element being employed at alltimes, the other only when the motors bear a certain relation to eachother, and aswiteh for connecting the elements together, in order toincrease the current-carrying capacity of the controlling resistance.

17. In combination in a control-circuit, a controlling-switch, arheostat therefor, and means for simultaneously increasing thecurrent-carrying capacity and decreasing the resistance of saidrheostat.

In witness whereof I have hereunto set my hand this 29th day ofDecember, 1897.

WILLIAM B. POTTER.

Vitnesses:

B. B. HULL, O. L. HAYNES.

